The present invention relates to an antisense oligonucleotide derivative which is useful as a pharmaceutical that inhibits the expression of human interleukin-6 receptor (IL-6R).
Human interleukin-6 (human IL-6) is a cytokine that was cloned as a factor that induces the final stage of differentiation of B cells to antibody-producing cells (Kishimoto, T. et al., Blood 74, 1-10, 1989). At present, it is known to have various effects, including induction of acute phase protein in the liver (Kishimoto, T. et al, Blood 74, 1-10, 1989).
In addition, IL-6 has been reported to be produced not only in lymphoid cells, but also in fibroblasts, vascular endothelial cells, urinary bladder carcinoma cell strain T24 and glioblastomas (Kohase, M. et al., J. Cell Physio. 132, 271-278, 1978; Meir E. V. et al., Cancer Res. 50, 6683-6688, 1990). Moreover, it also has a diverse range of target cells (Kishimoto, T. et al., Blood 74, 1-10, 1989).
In recent years, IL-6 has been reported to function as autocrine growth factor in myeloma cells (Kawano, M. et al., Nature, 332, 83-85, 1988). Moreover, similar reports have been made with respect to nephrocytoma (Miki, S. et al., FEBS Letter 250, 607-610, 1989).
On the other hand, the signal for cell growth or differentiation by human IL-6 is known to be transmitted to cells by means of human IL-6R and glycoprotein gp130 present on the cell surface (Taga, T. et al., Cell 58, 573-581, 1989; Hibi, M. et al., Cell 68, 1149-1157, 1990).
In recent years, as a method for suppressing the function of a gene that is the cause of a particular disease, the use of a oligonucleotide complementary to mRNA transcribed from DNA (antisense oligonucleotide) has been proposed to inhibit expression of said protein (Murakami, Chemistry 46, 681-684, 1991).
Moreover, as a means of eliminating problems such as the life, stability and rate of uptake into cells of antisense oligonucleotides, modified antisense oligonucleotides, such as methylphosphonate derivatives, in which the oxygen of a phosphate group of the nucleotide is substituted with a methyl group, and phosphorothioate derivatives, in which the oxygen group is substituted with sulfur (Murakami, Chemistry 46, 681-684, 1991) are known. In actuality, these antisense oligonucleotides have been observed to inhibit synthesis of viral protein (Agris, C. H. et al., Biochemistry, 25, 6268-6275, 1986).
Based on this concept, Levy, Y. et al. confirmed that the growth of myeloma cell strains, for which human IL-6 is a growth factor, is inhibited as a result of translation of mRNA for IL-6 being inhibited by antisense oligonucleotide (Levy, Y. et al., J. Clin. Invest., 88, 696-699, 1991).
However, an antisense oligonucleotide derivative that significantly inhibits expression of IL-6R in various cells in which IL-6R is expressed is not known.
Thus, the present invention is intended to provide an antisense oligonucleotide derivative that inhibits the expression of human IL-6R.
More specifically, the present invention provides a human IL-6R expression inhibitor comprising an antisense oligonucleotide derivative corresponding to at least nine consecutive nucleotide sequences that contain the nucleotide sequence of the portion that has a high possibility of being able to form a loop structure of mRNA that codes for human IL-6R.